1. Field of the Invention
The present invention relates to a driving apparatus of a so-called traction type or friction drive type, wherein torque transmission is realized with low noise and low vibration by utilizing shearing resistance of oil membrane or frictional resistance (when lubricant is not used) between cylindrical surfaces pressed to each other. The present invention relates to improvement of a driving apparatus of such a type.
2. Description of Related Art
Traction drive type driving apparatus has been known as a low noise driving apparatus. Conventionally, as a transmitting apparatus of such a type, for example, Japanese Patent Publication No. Sho 62-46742 discloses a driving force transmitting apparatus of a planetary roller type provided with an elastic roller. The transmitting apparatus disclosed in the Japanese Patent Publication No. Sho 62-46742, forces are exerted to the elastic roller having U-shaped cross section from both the sides so that the inner diameter of the roller is decreased so as to obtain pressing force.
Japanese Patent Publication No. Sho 51-25538 discloses a reduction device using frictional transmission wherein an input spindle and output spindle are opposed on a same axis, a plurality of rollers are disposed between an inner race integrally formed with the input spindle and a fixed elastically deformable outer race, a shaft with a holding ring for rotatably supporting the rollers is connected to the output spindle, an annular hydraulic chamber is formed between the outer race and a housing of the reduction device, and when frictional transmission is effected from the input spindle to the output spindle via the rollers, hydraulic pressure corresponding to the load of the output spindle is supplied to the hydraulic chamber so as to decrease the outer race in a radial direction, and radial pressure is applied to the rollers.